The present invention relates to mercaptoacyl aminolactam inhibitors of endopeptidases useful in the treatment of cardiovascular disorders and pain conditions.
Cardiovascular conditions which may be treated with compounds of the present invention include hypertension, congestive heart failure, edema and renal insufficiency.
Human hypertension is a disease of multiple etiologies. Included among these is a sodium and volume dependent low renin form of hypertension. Drugs that act to control one aspect of hypertension will not necessarily be effective in controlling another.
Enkephalin is a natural opiate receptor agonist which is known to produce a profound analgesia when injected into the brain ventricle of rats. Enkephalin is known to be inactivated by a group of naturally occurring enzymes known as enkephalinases or endopeptidases.
A variety of compounds known as endopeptidase inhibitors are useful as analgesics and/or in the treatment of hypertension. For example, European Patent Application 38,046 discloses enkephalinase inhibitors of the formula ##STR2## wherein R.sup.2 is lower alkyl or methylthiomethyl, Ph is optionally substituted phenyl and R.sup.4 and R.sup.5 are hydrogen or alkyl.
U.S. Pat. No. 4,513,009 discloses alpha amino acid derivatives of the formula ##STR3## wherein R.sup.1 can be alkyl, phenyl or thienyl, R.sup.2 is preferably hydrogen, alkyl, benzyl or benzyloxyalkyl and R.sup.4 can be alkyl or substituted alkyl. The compounds are said to have enkephalinase inhibiting and hypotensive activity. U.S. Pat. No. 4,740,499 discloses the use of thiorphan (a compound within the scope of U.S. Pat. No. 4,513,009 but having a terminal carboxy group) to enhance the activity of an atrial peptide.
U.S. Pat. No. 4,801,609 discloses mercapto-acylamino acids of the formula ##STR4## wherein R.sup.1 can be aryl or heteroaryl, R.sup.2 can be alkylthioalkyl or alkoxyalkyl and R.sup.7 and R.sup.8 can each be substituted alkyl or together can form a ring.
U.S. Pat. No. 4,774,256 discloses analgesic enkephalinase inhibitors of the formula ##STR5## wherein R.sup.2, R.sup.3, R.sup.7 and R.sup.8 can be alkyl, arylalkyl or heteroarylalkyl, or R.sup.7 and R.sup.8 can form a ring, and n can be 1-15. German Patent Application 3,819,539 discloses a variety of compounds, including those of a scope similar to the '256 patent wherein R.sup.7 and R.sup.8 form a ring; the compounds are said to be diuretics, natriuretics and blood pressure lowering agents.
It is known that the heart secretes a series of peptide hormones called atrial natriuretic factors (ANF) which help to regulate blood pressure, blood volume and the excretion of water, sodium and potassium. ANF were found to produce a short-term reduction in blood pressure and to be useful in the treatment of congestive heart failure. See P. Needleman et al, "Atriopeptin: A Cardiac Hormone Intimately Involved in Fluid, Electrolyte and Blood-Pressure Homostasis", N. Engl. J. Med., 314, 13 (1986) pp. 828-834, and M. Cantin et al in "The Heart as an Endocrine Gland", Scientific American, 254 (1986) pg. 76-81.
Angiotensin converting enzyme (ACE) inhibitors are another class of drugs known to be effective in treating some types of hypertension. ACE inhibitors are useful in blocking the rise in blood pressure caused by increases in vascular resistance and fluid volume due to the formation of angiotensin II from angiotensin I. For a review of ACE inhibitors, see M. Wyvratt et al., "Recent Developments in the Design of Angiotensin Converting Enzyme Inhibitors" in Med. Res. Rev., 5, No. 4 (1985) pp. 483-531.